August 21, 2012

Tam Pa Ling: modern humans in Southeast Asia at 63-46ka

I have become convinced that the roots of the Eurasian dispersal occurred at around 70 thousand years ago, from an earlier population of modern humans that had left Africa for the Levant and Arabia before 100 thousand years. So, the discovery of a new anatomically modern human from Southeast Asia that is directly dated to 63ka and can be no younger than 46ka is a welcome addition to the record.

The Tam Pa Ling skull would be of similar age to the Liujiang skull from China if the latter's 68ka age is accepted. So, now the case is much more secure for the presence of modern humans in the Far East in the interval between the 70ka Event, and the post-50ka symbolic revolution associated with the MP/UP transition. If we add to the equation the presence of an UP European-like skull at Qafzeh in Israel at ~100ka, and of the Nubian Complex in South Arabia at ~106ka, it is becoming increasingly difficult to accept ideas about either a 60ka coastal migration, or a late Out-of-Africa migration associated with the Upper Paleolithic that somehow replaced the people who lived all over Eurasia.

From the press release:

"It's a particularly old modern human fossil and it's also a particularly old modern human for that region," said University of Illinois anthropologist Laura Shackelford, who led the study with anthropologist Fabrice Demeter, of the National Museum of Natural History in Paris. "There are other modern human fossils in China or in Island Southeast Asia that may be around the same age but they either are not well dated or they do not show definitively modern human features. This skull is very well dated and shows very conclusive modern human features," she said.

No other artifacts have yet been found with the skull, suggesting that the cave was not a dwelling or burial site, Shackelford said. It is more likely that the person died outside and the body washed into the cave sometime later, she said.

The find reveals that early modern human migrants did not simply follow the coast and go south to the islands of Southeast Asia and Australia, as some researchers have suggested, but that they also traveled north into very different types of terrain, Shackelford said.

Uncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51–46 ka, and direct U-dating of the bone indicates a maximum age of ~63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic–modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at ~50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia.

10 comments:

So we find anatomically modern humans during a time period when there are Neanderthals in the Levant (Kebara Cave) and Europe, which are right at Africa's doorstep. I'd say this supports a generally southern migration route of early modern humans out of Africa, which need not be strictly coastal. West Eurasian groups would be a later offshoot of this OoA population, perhaps corresponding to the 40 kya bottleneck identified in the French in the recent paper.

This may be a good match for the Y-DNA/mtDNA found in Eurasia today. The oldest Y-DNA haplogroups (C, D) have a clear southern/eastern distribution; they're lacking in West Eurasia, where certain F lineages are instead very prominent. On the mtDNA side, West Eurasians carry haplogroup N, whereas deep branches of both M and N can be found in southern and eastern Eurasia.

So, most parts of West Eurasia don't seem to have been important in the early modern human expansion. Otherwise, it seems very odd that the uniparental markers found in West Eurasians, who actually live closest to Africa, are less diverse than those found in other Out-of-Africans. The OoA group may have originally migrated across the Bab el Mandeb 60-70 kya, when sea levels were much lower and the East African climate entered a dry period. They quickly expanded across South Asia, reaching Southeast Asia and Australiasia quite early on, and a subgroup of these Out-of-Aficans went on to colonize Europe, leading to the extinction of the Neanderthals.

West Eurasia was probably crucial in the UP transition. According to Ted Kandell, who's probably been following these things better than me:

"We know that G splits off of F* first (L69.1=T, etc.) then H and F2 ("F1" is missing in action) then F3+IJK. (F5 is part of South Indian F*, which should have a defining SNP now, finally). "

So, West Eurasia has the basal clade G, then H and F2 and F3 (South Asia), and then IJK into IJ (West Eurasia)+K. Then K into LT (West Eurasia) and non-LT.

It seems that the UP (F=most likely candidate) first happened in West Eurasia and spread from it to the rest of Eurasia. But, modern humans had dispersed deeper into Asia even before the UP (as D and C suggests).

"The find reveals that early modern human migrants did not simply follow the coast and go south to the islands of Southeast Asia and Australia, as some researchers have suggested, but that they also traveled north into very different types of terrain, Shackelford said".

As far as I'm aware the skull was found in the hill country of Laos. There is no connection to any coast at all. Any population adapted to exploit a coastal environment is unlikely to be found so far from it.

There is certainly nothing 'southern' about D. And even C can hardly be claimed to show indisputable evidence of much southern element. C5, the so-called 'Indian clade', could quite easily be 'SW Asian'. Its presence in India is largely confined to the northeast.

"On the mtDNA side, West Eurasians carry haplogroup N, whereas deep branches of both M and N can be found in southern and eastern Eurasia".

You'd be struggling to name a definitely 'deep brqanch' of haplogroup N in southern Asia. R is the only possibility, and it is far more likely to have sprung up in SE Asia than in South Asia. There is a gap between the two clusters, most likely explained as indicating the extinction of intermediates. How would this have happened in South Asia where such a variety of modern haplogroups survive?

"So, West Eurasia has the basal clade G, then H and F2 and F3 (South Asia), and then IJK into IJ (West Eurasia)+K. Then K into LT (West Eurasia) and non-LT".

I've been trying to make Maju see that for years. Thanks. The only thing I would add is that LT quite possibly actually originated somewhere in India, and K(xLT) next diversified somewhere very near Wallacea. And then P began its long trip back through South Asia.

There is a problem with seeing South Asia or even Eastern part of West Asia as strictly West Eurasian.

The current genetic affinity of South Asians may largely be the result of geoclimatic accidents of the post glacial era rather than their inherent affiliation.

There simply is no basis for classifying Eurasians into East and West for populations older than 20000. And even more so for > 40K. There were obviously genetic divisions or even races at the time but not necessarily along the East and West division.

The same argument for the Asian origin of CT can be applied to East and West Eurasians.Of D E C F, only E can be said to be West Eurasian and F partially so if you count South Asia as East Eurasians.

This is not to argue for inclusion of South Asians in East Eurasians but to illustrate the pitfalls inherent in this mode of thinking.

K lineages, more specifically MNOPS, occur in all "East Eurasian" populations which include Australiains and other Oceanians according to the way the terminology is used in this forum.

To see this as West Eurasian males(Caucasoid males in Klyosov's) INDEPENDANTLY imposing their way onto various East Eurasian female populations sounds like a comical amateur fantasy befitting Klyosov.

It is found with high frequency in the Andamanese and Indian tribals. D/DE is found in southwestern China, which is fairly southern. Anyway, my point was that you find a higher diversity in the southern and eastern parts of Eurasia than in West Eurasia, which is actually located closest to the African homeland of modern humans.

You'd be struggling to name a definitely 'deep brqanch' of haplogroup N in southern Asia.

The term used was southern Eurasia, by which I'm not simply referring to the Indian subcontinent. You do find the deep branches in Southeast Asia (and also Australasia). Again, their higher mtDNA/Y-DNA diversity compared to modern West Eurasian is odd assuming their ancestral population was deeply rooted in West Eurasia, and not the other way around. Interestingly, we do also find very early AMHs in Southeast Asia (Southeast Asians possess divergent M and N lineages).

"It is found with high frequency in the Andamanese and Indian tribals. D/DE is found in southwestern China, which is fairly southern".

And Tibet/Mongolia evidently:

http://en.wikipedia.org/wiki/Haplogroup_D_%28Y-DNA%29

Quote:

"Haplogroup D is also remarkable for its rather extreme geographic differentiation, with a distinct subset of Haplogroup D chromosomes being found exclusively in each of the populations that contains a large percentage of individuals whose Y-chromosomes belong to Haplogroup D: Haplogroup D1 among the Tibetans (as well as among the mainland East Asian populations that display very low frequencies of Haplogroup D Y-chromosomes), Haplogroup D2 among the various populations of the Japanese Archipelago, Haplogroup D3 among the inhabitants of Tibet, Tajikistan and other parts of mountainous southern Central Asia, and paragroup D* (probably another monophyletic branch of Haplogroup D) among the Andaman Islanders. Another type (or types) of paragroup D* is found at a very low frequency among the Turkic and Mongolic populations of Central Asia"

So we possibly have five D haplogroups. The one in the 'Indian tribals' is actually Tibetan and found (only?) in Tibeto-Burman speaking people, presumably D1. D2 is confined to the north, Japanese in particular. D3 is found in Southwest China, Tibet and in Central Asia. The Andamanese and Central Asian D*s are probably two separate single haplogroups. So really only two D haplogroups can be claimed as 'southern'. And this abstract has an interesting comment on the matter:

http://www.cell.com/AJHG/abstract/S0002-9297%2807%2960944-6

"In contrast, whereas haplogroup D is completely absent in Nepal, it accounts for 50.6% of the Tibetan Y-chromosome gene pool".

That requires some explaining if you're going to call D 'Southern Eurasian'.

"my point was that you find a higher diversity in the southern and eastern parts of Eurasia than in West Eurasia, which is actually located closest to the African homeland of modern humans"

I agree it is impossible to claim D as being West Eurasian. But it's not 'southern' either. However it is most likely that DE's distribution was at one time virtually geographically continuous but it has been separated into D and E at opposite ends by extinction of intermediate forms. Either by expansion of CF or by climate change.

I agree, although not actually 'Australasia', more specifically Australia. I think only R-derived haplogroups (specifically P and B4a1) are found elsewhere in Australasia. But deep N haplogroups are absent in the region between SE Asia and SW Asia.

"Again, their higher mtDNA/Y-DNA diversity compared to modern West Eurasian is odd assuming their ancestral population was deeply rooted in West Eurasia"

It is not that odd if you remember that much of Western and Central Eurasia suffered an extreme climate event which would have severely reduced population, and so haplogroup diversity.

"Interestingly, we do also find very early AMHs in Southeast Asia (Southeast Asians possess divergent M and N lineages)".

Southeast Asia would have suffered less with the climate cooling and increased aridity. In fact such climatic conditions may have improved the habitability of the region.

With regard to y-chromosome lineages, it appears to me as if the Sons of K may have stampeded eastward at some point. Could it have been an exodus from the Levant, in response to massive eruptions of Mediterranean volcanoes that took place around 40,000 bp? Their descendants today are found scattered from Kurdistan/Caucasus, across India, to Oceania and the Americas. (The Laos skull predates this, so I would guess it is probably C or D?)

"it appears to me as if the Sons of K may have stampeded eastward at some point".

I would think 'westward' was more likely. Most K haplogroups are SE Asian or beyond Wallace's Line. K1 is South Asian but very rare, and very widespread. K2 is found in Australia/New Guinea, K3 in Melanesia and Indonesia and K4 primarily in Bali. Two members of the other branch of K, MNOPS, are also basically confined to beyond Wallace's Line. So that makes K's origin most likely somewhere in SE Asia, not in West Asia.

"Their descendants today are found scattered from Kurdistan/Caucasus, across India, to Oceania and the Americas"

The only 'descendants' scattered so widely are haplogroups descended from just NO and P. The others are all fundamentally Wallacean.

"(The Laos skull predates this, so I would guess it is probably C or D?)"

Possibly, but we cannot be sure. K does seem to have reached SE Asia after those two.

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